1. Field of the Invention
The present invention relates to a method and device to measure the optical transmission factor of a tinted glass panel by reflection.
2. Description of the Prior Art
Usually, the optical transmission factor of a glass panel is ascertained by direct measurement of the ratio between the flux of an electromagnetic radiation transmitted by this panel and the flux of the incident electromagnetic radiation that creates it.
However, for this purpose, the incident electromagnetic radiation transmitters and the receivers for the transmitted electromagnetic radiation should be placed on either side of the glass panel to be examined. These standard systems cannot easily be used if the glass panel is a wall between two environments, with one environment subjected to adverse weather and/or severe ambient conditions while the other environment is a shielded environment or chamber. This is the case, for example, when the glass panel forms the windshield of a motor vehicle or an aircraft: the optical transmission factor of this glass panel has to be determined regularly to ensure the optimal functioning of accessory driving or piloting equipment (for example fog detectors or similar instruments) calling for a precise knowledge of the transmission factor of the glass panel. For these standard systems entail the installation of the receivers in the external environment or subjecting them to severe environmental conditions and this, of course, considerably increases the cost of their use.
An object of the present invention is to remove the above-mentioned drawbacks by implementing a method and device to determine the optical transmission factor of a glass panel by reflection.
Another object of this invention is the implementation of a method and a device to determine the transmission factor of a glass panel by reflection, wherein all the equipment used is located on one and the same side of the glass panel, in the shielded environment.
Another object of the present invention is the implementation of a method and a device making it possible, when changing the glass panel that forms the windshield of a motor vehicle or an aircraft, to directly determine the transmission factor of this glass panel by reflection, in order to provide for the corresponding control of accessories of the vehicle or the aircraft, the functioning of which depends on the value of the above-mentioned factor.
Another object of the invention is also the implementation of a method and device which can be used, when there exists a glass panel with a shade and/or opacity variable according to ambient luminosity, to make a corresponding check on accessories of the vehicle or aircraft, the functioning of which depends on the value of the above-mentioned transmission factor depending on the tint and/or opacity of said panel.